The present invention refers to a new manufacturing solution for a plastic hinge which is particularly advantageous for manufacturing rigid cases in general, and in particular rigid cases for glasses, by giving it an absolutely original appearance and by realising an absolutely new technique through which the case is snapped open and closed, even with the type of plastic hinge which is applied to any type of rigid half-shells.
The main characterising feature of the present invention is to provide for the manufacturing of a single plastic element to join the two half-shells of a case, said element consisting of two surfaces (or xe2x80x9cwingsxe2x80x9d) to be fixed to the edges of the half-shells and joined each other longitudinally by an intermediate U-shaped surface having a minimum thickness suitable for giving it the necessary flexibility, said surfaces being further hooked together by one or more springs aiming to, flex said surfaces to make the half-shells snapping in the opening or in the closing position.
The best way to protect and keep glasses or other fragile or valuable things is undoubtedly to put them in a rigid metal case of lidded box type, that generally consists of two half-shells, made on a preformed laminate, which are suitably covered by cloth, leather, simulated leather or similar materials and which are hinged each other at the edge opposite to the opening one.
The traditional technique of joining and hinging the two metal half-shells of said metal lidded box uses a normal hinge consisting of an element with a flat surface, to be fixed to the edge of a half-shell, provided with a series of small eyelets alternated with free spaces to be housed, aligned and hinged to the eyelets of the other part of the hinge, whose flat surface is fixed to the corresponding edge of the other shell to be joined and hinged.
Some cases of the above mentioned type, instead of being provided with a single hinge fixed along the whole back side of the case, have two distinct hinging elements, each of which is however provided with a flat surface to be fixed to the edge of the two half-shells and with an eyelet to be aligned and hinged to the other eyelet, with the same function of hinging.
The individual hinging elements are in turn fixed to the respective half-shell through seaming tabs realised on the metal edge of each case and suitably riveted after having gripped the flat surface of the hinge elements, which are then covered and made invisible by the covering fabric.
In the lidded metal boxes of the more accurate and prestigious type, the known hinging technique includes the application of one or more spring which, by hooking onto the respective and opposite edges of the hinge, give a useful snap action on opening and closing phases of the two half-shells.
The technique described up to now obviously carries out the necessary hinging action, as described above; however it has the disadvantage that the back edge of the case shows the row of hinging eyelets that inelegantly protrudes or at least shows up, affecting the overall appearance, often very accurate, with which a case of this type is finished.
Furthermore, as time passes, the above mentioned traditional hinges present rusting and noise problems that devalue the whole case.
An alternative technique for manufacturing lidded box cases has been introduced with the use of new plastics suitable for ensuring a sufficient stiffness to the two half-shells, as well for allowing that special configurations raised on their surfaces are created.
The joining and hinging of the half-shells of lidded-box cases made in plastic is generally allowed by the presence on an edge of these half-shells of special housings into which the surfaces supporting and fixing the hinging elements are inserted, while their eyelets must however be aligned to be hinged.
The final appearance resulting from this technique of joining and hinging the plastic half-shells, as the whole appearance in general, is certainly worsened when compared to the appearance of joining metal half-shells, as described above.
In any case, this alternative technique also has the disadvantage of not allowing the application of elastic systems that allow the plastic case to be snapped open and closed.
The introduction of new, stronger plastics has recently allowed to make hinges of plastic that, instead of being based on hinging a series of eyelets of two opposing aligned parts, are based on the use of a single hinging part made of one of these suitable plastics, comprising two surfaces to be fixed to the edges of the half-shells and joined by a thin intermediate surface that can be bent several times without breaking.
This improved hinging technique certainly ensures a better appearance for the back of the case, even if it does not allow elastic systems to be provided, however, for snapping the two half-shells open and closed.
What is more, this technique has never been used to join a pair of metal half-shells, since these half-shells do not provide for suitable recesses to house and to anchor said plastic hinge.
All these problems and others can be solved by a plastic hinge providing for a continuous longitudinal bend in the middle, which gives a new and original appearance to the back of the case, especially if used on metal half-shells of the highest quality, as well as ensuring a perfect operation for the hinging system that is complete with a snap opening and closing action.
In fact, the main purpose of the present invention is to allow the manufacturing of a back surface of a rigid lidded case having an appearance free of an unattractive visible row of back hinging rings, since it is provided with one or more continuous portions of a linear hinging element which can be applied especially to a pair of metal half-shells.
Another purpose of the present invention is to allow the manufacturing of rigid, lidded cases provided with one or more linear hinges, which however allow a closing and opening snap of its half-shells.
A further purpose of the present invention is to be able to apply the same type of linear hinge both to metal half-shells and to plastic ones, ensuring however, even over a period of time, both the quality and precision of the appearance and the functionality, silence and snap action of the hinge.
Last, but not least purpose of the present invention is to reduce to a minimum the parts that make up the hinge, reducing the costs of production and of providing the hinges to the half-shells of the case, thus realising a rigid lidded case that is both precise in appearance and provided with a hinge which is simple to make and apply.
A plastic hinge for cases, especially for glasses cases, is disclosed, which is made of a single element, made of a suitable plastic material, suitable for joining the half-shells of a case. Said single element consists of two flat surfaces for fixing and joining the back edges of the half-shells and of an intermediate U-shaped surface for flexing said flat surfaces and is provided with teeth to anchor one or more springs that give it a closing stability and a snap movement.